Powder metallurgical compositions are well known for the production of powder metallurgical parts. Production of powder metallurgical parts involves filling of the powder in a compaction tool, compaction of the powder and subsequent sintering of the compacted body. A prerequisite for filling of the powder is that the powder is free-flowing and has a sufficient flow. A high flow rate of the powder is essential to obtain a high production rate giving lower production costs and a better economy for each part produced.
Another factor which is essential for the production efficiency and economy is the apparent density. Apparent density is essential for the tool design. Powder with low apparent density needs higher filling height which results in unnecessarily high pressing tools, and this in turn will result in longer compaction strokes and lower pressing performances.
Agents which improve the flow properties are previously known. Thus the U.S. Pat. No. 3,357,818 discloses that silicic acid may be used to this end. The U.S. Pat. No. 5,782,954 discloses that metal, metal oxides or silicon oxide can be used as flow agents.
It is an object of the present invention to provide a powder metallurgical composition with improved powder properties such as flowability and apparent density.